The present invention relates to a mounting system for a stator vane in a turbine nozzle having a plurality of radially extending, circumferentially spaced vanes to direct the flow of hot gases emanating from a combustion chamber onto the blades of a turbine wheel.
It is well-known to provide at least one row of stationary vanes adjacent to the exit of a combustion chamber in a gas turbine engine to direct the gases emanating from the combustion chamber onto the blades of a turbine wheel. The nozzle vanes serve to direct the gases onto the movable blades in a direction which increases the efficiency of the turbine wheel.
Quite obviously, the gases emanating from the combustion chamber are extremely hot thereby causing the nozzle vanes and the blades of the turbine wheel to undergo substantial thermal and mechanical stress. It is also known to provide the nozzle vanes, as well as turbine blades, with a cooling fluid, such as air withdrawn from a compressor stage of the gas turbine engine. Typically, such known cooling systems involve directing the air internally into the hollow vane or blade such that it impinges on the inner surface of the vane or blade. The cooling fluid may then be extracted from the interior of the vane or blade by holes through a surface of the vane or blade, or by passages defined by the vane or blade mounting system. Since the cooling fluid is at a lower temperature than the vane or its mounting structure, exposure of this system to the cooling fluid may add additional mechanical and thermal stresses to the vane and its mounting system.
U.K. Patent Application 2 210 415 discloses a cooled turbine vane comprising a cooling sleeve located in the interior of the hollow vane wherein one end of the sleeve is affixed to an outer platform which is, in turn, attached to the vane, while the opposite end of the cooling sleeve is unattached. In this particular design, the external vane casing must withstand both high temperature and mechanical stresses.
U.S. Pat. No. 4,288,201 discloses a vane cooling structure wherein an inner cooling tube has one end attached to one of the blade platforms, while a cooling gas inlet sleeve is fixedly attached to the opposite vane platform.
It is well-known in the art that the mechanical strength of an article decreases at high temperatures.